This invention relates generally to aircraft departure and landing noise abatement procedures, and more specifically, to methods and systems for implementing location based noise abatement procedures.
One means to reduce aircraft noise is to reduce thrust in the proximity of the noise-sensitive receiver. The relative position of the aircraft to a fixed receiver on the ground is an important factor in the resulting noise measured at the receiver location.
Current departure noise abatement procedures utilize aircraft altitude, or height, as a trigger for thrust reduction, thrust restoration, and subsequent aircraft acceleration. However, the location where an aircraft attains a specific altitude can vary due to operational and environmental factors. These operational and environmental factors can reduce the effectiveness of the altitude based noise abatement procedures, and may include, for example, aircraft type, a loading of the aircraft (passengers, cargo, and amount of fuel), and weather related conditions, just to name a few.
Due to the varying of the above mentioned operational and environmental factors, calculation and implementation of altitude-based thrust reduction cues are typically based upon conservative environmental and operational conditions. These conservative conditions ensure a thrust (and therefore noise emissions) associated with the aircraft engines is reduced to meet targeted noise constraints at one or more fixed ground receiver locations, without requiring calculating thrust reduction heights for actual environmental and operational conditions. To meet targeted noise constraints, specific departure noise abatement procedures may be based upon, and/or require the calculation of specific thrust reduction altitudes for a given set of operational and environmental conditions. Also, the procedures utilized to meet the targeted noise constraints, both for thrust reduction and restoration may be performed manually, and may not always be accurate and consistent. However, it is believed software tools are being developed that will calculate thrust reduction/restoration height cues that account for flight-specific operational and environmental conditions.
Current cues for thrust reduction, whether automatic or manual, are based upon the aircraft height above the ground, not relative lateral position to the receiver. A single, conservative, height-based reduction/restoration cue does not account for winds, piloting technique, non-design weights or other environmental and operational conditions.
Whether manually calculated or computer based, since conservative calculations are used, the aircraft that utilize these procedures tend to reduce thrust earlier than is necessary, and restore thrust later than is necessary, to meet the targeted noise constraints. Reduction of thrust earlier than necessary, and restoration of thrust later than necessary, reduces the efficiency of aircraft operation, for example, during take-off and landing maneuvers.
Additionally, flight-specific thrust reduction and restoration procedures should be calculated using current operational and environmental data, and with regard to pre-calculated thrust reduction and restoration procedures, such data may not be accurate at time of departure.